Knitted paper fabric



June 27, 1967 Filed Nov. 23, 1966 R. A. WILLER KNITTED PAPER FABRIC 2 Sheets-Sheet 2 Y @MQQ United States Patent 3,327,502 KNITTED PAPER FABRIC 1 Robert Alfred Willer, Neenah, Wis., assignor to American glan Company, New York, N.Y., a corporation of New ersey Filed Nov. 23, 1966, Ser. No. 596,658 Claims. (Cl. 66202) This is a continuation-in-part of my copending application Ser. No. 369,396 filed May 22, 1964, now abandoned.

The present invention relates to improved knitted paper fabric and methods for producing the same; and, in particular, to a knitted paper wiping cloth and an economic and efiicient method of producing such a cloth.

There is a considerable market for wiping cloths. Paper towels have become standard items in the American household and are used extensively for wiping spills, cleaning tables and the like. Some paper products are even used as disposable wash cloths both in the kitchen and in the bathroom. Industry uses a substantial volume of wipes for cleaning machinery and work-pieces as well as for wiping hands and spills.

However, these uses require different types of wipes, depending upon the wiping job they are to perform. For example, paper toweling would have insufficient wet or dry strength to be used as a wash cloth or machinery wipe. The rags or manufactured wipes used by industry would be considered too coarse for general acceptance by the household public. Further, industrial wipes are presently considered relatively expensive, thereby creating a demand for a less expensive but efilcient industrial wipe. In general, therefore, there is a market for a universal wiping cloth that is relatively inexpensive, presents a nice appearance yet is strong and highly absorbent, at least to such liquids as water and oil.

It is therefore an object of the present invention to provide a wiping cloth meeting most if not all of the demands of the marketplace.

Another object is to provide a wiping cloth which is relatively simple and inexpensive to manufacture yet is strong both in a wet and dry condition, and highly absorbent.

Still a further object is to provide a relatively simple and economically feasible method of making such a wiping cloth.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof. 4 The above objects are accomplished by dividing a paper web into a number of individual, narrow, flat strips, wetting the strips with a solution or suspension of a particular glycol ester, combining a plurality of the wet, individual strips to form an essentially flat yarn, knitting the flat yarn into a fabric while it is still wet from the gylcolester solution and subsequently dividing the fabric into individual wiping cloths. The glycol ester solution acts not only as a lubricant enabling the paper yarn to be knitted, but also, after evaporation of the volatile moiety of the solution in cooperation with the multitude of exposed cut edges of the paper in the knitted fabric, greatly enhances the oil and water absorbency of the ultimate knitted wiping cloth.

Referring to the drawings:

3 ,327,502 Patented June 27, 1967 FIGS. 1, 2, 3 and 4 are schematic perspective views illustrating, in respective sequence, the method of the present invention for producing knitted paper fabric; and

FIG. 5 is an enlarged fragmentary view of the knitted paper wiping cloth of the present invention.

As a preferred or exemplary embodiment of the instant invention, numeral 10 designates a roll of paper, used as a starting material in the present method, which is unwound and continuously moved by driven rollers 12 in the direction shown by arrows 14. The paper web from roll 10 is fed continuously through idler rolls 16 and 18 into a slitting device 20 which preferably constitutes a series of spaced adjustable disk shaped cutters and which slits the web into a number of individual flat strips or strand 22. Idler roll 16 is provided with collars to ac curately guide the web into the slitting device. The cutters may be rotated by any suitable driving mechanism. The slitted flat strands of paper 22 are then passed through guide means 24 and 26 which separate the individual strands. The guide means 24 and 26 are shown to include vertically disposed spacing pegs 28 and 30, but any equivalent means may be used. The strands are then continuously passed through a wetting and lubricating medium 32 of a composition to be more fully described hereinafter. The strands are passed under rubber roller 34 and thereby caused to be submerged in medium 32, which is contained in vessel 35. Two of the softened and lubricated wet strands are brought together and then continuously fed through guide means 36 to form a number (less than the number of strands 22) of substantially flat yarn elements 38. These plural-strand yarn elements are fed into a knitting device 40 wherein they are knitted into a fabric or material 42 while still in the softened, lubricated condition. The knitted material 42 which continuously emerges from the knitting device is then formed into a roll 44. The knitted fabric on roll 44 is subsequently unreeled and cut, by any suitable means, such as shears, into appropriately sized pieces, for example 12 inch squares, to form individual wiping cloths 43.

If desired, the paper 10 may be slit in a separate operation and thestrips wound on bobbins. The knitting is then carried out by continuously lubricating and softening the strips as they are unwound from the bobbins and then combining strips to form the yarns and thereafter knitting the yarns while in integral connection with the material on the bobbins.

From the view of FIG. 4 of the fragment of the knitted wiping cloth 43, it is seen that the yarn in the knitted cloth comprises two flat untwisted strands of paper. The yarn may contain more than two strands, the maximum number of strands included depending upon the bulk and weight desired in the knitted fabric. For the knitted articles contemplated by the present invention, up to six strands and preferably two or three strands are used. Each of the strands has two opposed surfaces 46 formed in the paper making operation and two opposed essentially raw cut edges 48 formed in the slitting operation. If calendered paper is used as a starting material, surfaces 46 will be calendered, and thus will have a smoother finish than edges 48. While the knitted wipe portion shown in FIG. 4 is a plain or jersey stitch, other well-known knitting patterns may be substituted therefor.

The plural strands in each flat yarn element in the knitted fabric insure the exposure of a multitude of raw cut edges. Each of these raw cut edges acts as an absorbcut surface or site which, in conjunction with the glycol ester in and on each strand described more fully hereinafter, provides the knitted fabric of the instant invention with its superior absorbency.

Any paper having reasonably high wet strength has been found suitable for the practice of this invention. In practice it has been found desirable that the wet tensile strength of the paper be at least 25% of the dry strength. Papers both sized and unsized, calendered and uncalendered, are suitable as materials for use in the present method so long as they posses the necessary wet strength. However, because of the greater absorbency, unsized paper is preferred. The caliper of paper which successfully can be used varies from relatively thin tissue paper to comparatively thick paperboard. Papers ranging in weight from 10 pounds per 3,000 ft. ream to 40 pounds per ream have been found preferable for the practice of this invention, while papers having a weight as low as 6 pounds per ream can be knit, and paperboards having a weight of. 100 pounds per ream have been found to knit only with difiiculty. The width of the slitted strips is selected in accordance with the Weight and bulkiness desired in the fabric. Widths ranging between inch and inch have been found suitable. As a general proposition, the greater the number of strands included in each yarn element, the thinner should be the strand and/or the lighter should be the caliper of the paper.

While the dry paper has a comparatively low coefficient of friction the same cannot be knitted because it is not soft enough to pass through a knitting mechanism and thus cannot be formed into a fabric. The use of water and related softening media such as salt, or acid solutions or alcohols are also ineffective because, although the same will soften the paper, the paper is not lubricated and therefore does not accommodate itself to satisfactory performance in a knitting machine. It has been found that liquid media, i.e. solutions or suspensions, which will reduce the sliding coefficient of friction of a paper to a value less than 80% of this coefficient of the same paper when wetted by water provides sufficient lubricity for knitting.

A variety of substances were found which provided the yarn with the necessary lubricity for knitting. Surprisingly, however, it was found that a limited class of compositions provided both the lubricity necessary for knitting the yarn and also water and oil aflinity to the yarn so that the resulting knitted fabrichad enhanced absorbency for these liquids. The compositions found providing this dual function are mixtures of the fatty acid monoesters of polyethylene glycol wherein the fatty acid moiety has from 15 to 200 carbon atoms and the glycol moiety of one ester in the mixture has a molecular weight of about from 1,000 to 2,000, and the glycol moiety of the other ester has a molecular weight of about from 100 to 600. Particularly preferred is a mixture of the monoester of a polyethylene glycol having a molecular weight of approximately 1,540 and stearic acid andthe monoester of a polyethylene glycol having a molecular weight of approximately l and stearic acid.

These esters are preferably applied to the strips 22 as a dilute aqueous solution or colloidal suspension ranging from about to 15% by weight of the ester in water. The higher molecular weight glycol ester predominates in the mixture, being present in an amount of, by weight, about from 2 parts to parts per part of the lower molecular weight glycol ester and preferably about 5 parts per part of lower molecular weight glycol ester. After knitting and drying, the fabric contains, both as a coating on and as an impregnant in the strands 22, about from 1 to 5% and preferably about 3.5% of its weight of the mixed ester in substantially the same weight ratio of higher molecular weight ester to lower molecular Weight ester disclosed immediately above.

When the untwisted paper yarn used in the process is knitted into a fabric, it has been found that the fabric has 4 much greater strength than might be expected for a material formed from narrow strips of a relatively weak material such as paper. The knitted fabric has a somewhat abrasive texture due to the presence on the surface of the fabric of a multitude of slightly protruding cut edges, which, hardened in drying, provide a large number of tiny scraping elements. However, these scraping elements, while they tend to cut through dirt or grime, are still sufficiently soft so as not to injure any underlying surface such as hands or work-pieces. This distinct advantage for a wiping cloth is in addition to the previously mentioned superiority in water and oil absorption resulting from the exposed relation of these cut edges and the glycol-fatty acid monoester mixture in and on the yarn. In addition to providing greater absorbency, increasing the number of strips in each yarn element of the knitted material also increases the bulk and softness of the fabric as compared to fabric having the same amount of material per unit area of fabric but made from a lesser number of wider strips.

In order to coat and at least partially impregnate the strips 22 with the ester solution, it has been founddesirable to completely immerse the strips in the aqueous medium. Other techniques such as spraying or the use of a flooded nip can also be employed, so long as softening and lubrication sufficient to produce knittable yarn is achieved. Since the yarn remains softened only while in the moist condition, it is necessary that the yarn be fed directly and continuously to the knitting mechanism while moist with the softening and lubricating medium. Subsequent drying of the knitted fabric removes the water but the glycol ester mixture remains to improve absorbency.

Standard knitting machinery, such as a revolving cylinder knitter of the type disclosed in US. Patent 3,214,943, has been found to be suitable for carrying out the knitting step of the present invention. Satsifactory results have been achieved operating revolving cylinder knitters at strip feed speeds which are standard for knitting apparatus, for example 300 feet per minute.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and it Will be apparent that various changes may be made in the form, construction and arrangement of the parts of the article and that changes may be made in the steps of the method described and their order of accomplishment without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. A knitted fabric adapted to be divided into wiping cloths comprising knitted yarn wherein each yarn element includes a plurality of flat, untwisted paper strips exposing a multitude of cut edges, said strips being coated with and having absorbed therein a glycol ester composition which imparts to said yarn lubricity for ready knittability and, in cooperation with said out edges, a high rate of water and oil absorbency; said ester composition comprising a mixture of a major portion of a fatty acid monoester of a polyethylene glycol having a molecular weight of from 1,000 to 2,000 and a minor portion of a fatty acid monoester of a polyethylene glycol having a molecular weight of from to 600, the fatty acid moiety of said esters having from 15 to 20 carbon atoms.

2. The knitted fabric set forth in claim 1 wherein said yarn element includes from 2 to 6 paper strips.

3. The knitted fabric set forth in claim 2 wherein said major portion ester is the monostearate ester of a polyethylene glycol of approximately 1,540molecular weight and said minor portion ester is the monostearate ester of a polyethylene glycol of approximately 100 molecular weight.

4. The knitted fabric set forth in claim 3 wherein said yarn includes, by weight, about 2 to 10 parts of said higher molecular weight ester per part of said lower molecular weight ester.

5. The knitted fabric set forth in claim 4 wherein said ester mixture is present in said fabric in an amount of about from 1 to 5% by Weight.

References Cited UNITED STATES PATENTS Berndt et a1. 117139.5 Smith et a1. 117-1395 Marks 2876 West et a1. 66169 X Keller et a1 117138.8 Marks 66125 Niemer et a1 66202 MERVIN STEIN, Primary Examiner.

5/1952 0 k t 1 -117 139.s H1953 f i f aL 57 153 10 R. FELDBAUM, Assistant Examiner. 9/1954 Schlatter 117 139.5 

1. A KNITTED FABRIC ADAPTED TO BE DIVIDED INTO WIPING CLOTHS COMPRISING KNITTED YARN WHEREIN EACH YARN ELEMENT INCLUDES A PLURALITY OF FLAT, UNTWISTED PAPER STRIPS EXPOSING A MULTITUDE OF CUT EDGES, SAID STRIPS BEING COATED WITH AND HAVING ABSORBED THEREIN A GLYCOL ESTER COMPOSITION WHICH IMPARTS TO SAID YARN LUBRICITY FOR READY KNITTABILITY AND, IN COOPERATION WITH SAID CUT EDGES, A HIGH RATE OF WATER AND OIL ABSORBENCY; SAID ESTER COMPOSITION COMPRISING A MIXTURE OF A MAJOR PORTION OF A FATTY ACID MONOESTER OF A POLYETHYLENE GLYCOL HAVING A MOLECULAR WEIGHT OF FROM 1,000 TO 2,000 AND A MINOR PORTION OF A FATTY ACID MONOESTER OF A POLYETHYLENE GLYCOL HAVING A MOLECULAR WEIGHT OF FROM 100 TO 600, THE FATTY ACID MOIETY OF SAID ESTERS HAVING FROM15 TO 20 CARBON ATOMS. 